I wish reviewers would update their reviews, problems mentioned were fixed...
If you like the Mellotron M-Tron is THE VSTi to get.
Installation is simple, you even have choices whether not to install various tape libraries. Install all of them if you decide to buy M-Tron as they are all good. I got the two additional libraries with M-Tron. They too are worth the cost. In particular Volume 2 has a bunch of custom sets and Chamberlin samples as well.
I've read of problems with M-Tron and I do have an intermitant one, on D4/Eb4 the same note plays on two different patches. This is a bummer but the vast majority of patches do not exibit this behavior. Most of the performance news is good. On a Celeron 600 playing 5 notes I couldn't get CPU useage past 5 - 9% in Orion Pro and Cubase VST 5.1. The quality of sounds varies greatly, sometimes within the same set of samples.
This however is accurate as volume, tone and noise issues plagued Mellotrons and other tape based keyboards. The samples for M-Tron have been cleaned up while leaving the essential Mellotron sound intact.
Choirs, violins, piano! and a host of other 'tron samples are dead ringers for the original Mellotron.
Another restriction which is accurate to the Mellotron design is the sample length of 8 or less seconds. This is a good thing as it becomes too easy with traditional looped samples to play the Mellotron like any other traditional synth. The thing is the Mellotron was it's own unique instrument with it's own unique playing style. Patches range from 23 - 36 notes. These seeming restrictions are exactly how the real instrument was played. It is the details that make M-Tron so appealing.
There aren't many controls, attack and release faders, volume, general tone and pitch knobs and a multi purpose 3 way switch for different operation modes. It's a simple yet beautiful system and the closest one will come to a real Mellotron in mint condition.